Potential redundant key comparisons in flat_hash_map::operator==

[HUD-Software]

While profiling code comparing two flat_hash_map instances, I noticed that during the execution of operator==, each key seems to be compared twice:

First, when calling find() on the second map to locate the corresponding element.

Then, when comparing the value_type (i.e., std::pair<const Key, Value>) objects themselves, which compares both key and value.
Since the key has already been looked up via find(), this second key comparison seems redundant.

Is this expected behavior for compatibility/generalization reasons, or would you consider optimizing operator== to avoid comparing the key twice when possible?

Example of optimized pseudocode (to avoid redundant key comparison):

if (map1.size() != map2.size()) return false;
for (const auto& [k, v] : map1) {
    auto it = map2.find(k);
    if (it == map2.end() || it->second != v) return false;
}
return true;

I’m aware that the current implementation probably favors code generality and reusability, but given that flat_hash_map aims for performance, this might be an area worth considering.

What’s your take on this?

Thanks again for your work!